The bioinorganic chemistry of actinides in blood

The behaviour of actinides (An) in mammalian blood is controlled largely by their strong tendency to hydrolyze and form complexes at physiological pH (similar to 7.0). Except for U(VI) and Th(IV), with 70-90% associated with blood cells, the plasma is the predominant transport medium for An in blood. Numerous studies have demonstrated that, in human and animal blood plasma, Pu(IV), Th(IV), Pa(V), U(VI), and Np(V) appear to bind strongly to the iron-transport protein transferrin (Tf), although the binding characteristics may vary from element to element. The trivalent An, Ac(III), Am(III), Cm(III) and Cf(III), apparently bind to Tf, but also to other proteins, and the association with transferrin appears to be much weaker than that of the other actinides. (C) 1998 Elsevier Science S.A.